2Plant organ systems Root system - Ususally underground 2. Shoot system -usually above ground
3Shoot and Root systems working together To move nutrients, water and hormones throughout plants via vascular bundles (xylem + phloem)
4Marcello Malpighi’s experiment (1686) Question raised: what happen if the flow of materials in the vascular bundles was interrupted?Describe what happen in the pictureRemoving phloem led to swelling of tree bark above the cut.Sweet fluid dripped out of the swellingTree died a few weeks after the experimentWhat do you think happened?
5Movement of materials in vascular bundles Phloem moves sugars from where to where?From leaves to other organsXylem moves water and minerals from where to where?From roots to other organsWhat would the results have been if the xylem is removed?Water from root can’t reach leaves, no photosynthesis take place. Plant will also die out
6What happen to plant when no or too much water? No water:Nutrients in soils can’t be dissolved and taken upNo water for photosynthesisPlants will dieToo much water:Root cells die as not enough O2 in soil to get energy from cellular respiration
7How is water moved through xylem? Water transported up the plant against gravityWater first absorbed by the root hairsWater and nutrients then enter the root by osmosis (= the movement of water from a place of higher WATER concentration to a place of lower WATER concentration) until it they reach the xylemBefore entering xylem, water and nutrients are filtered through the waxy cell membranes of the endodermis.
8How is water moved through xylem? (cont.) A combination of root pressure, loss of water through stomata (leaf openings) and adhesion and cohesion properties of water helps move water up the plants.Adhesion: ability of water molecules to stick to certain surface (e.g. xylem’s wall)Cohesion: ability of water molecules to stick to one another
9How is sugar moved through plant? Glucose from leaves must first converted into sucroseSucrose is soluble in water and is transported through plants via phloemWhen reaching root, sucrose is converted into starchIf plants needs starch from root, starch must be converted back to sucrose because starch is water insolubleStarch is then transported upward as sapCollecting maple sap
10How do shoot and root systems depend on one another? What is produced in the leaves that needed by the rest of the plants?Explain how without the shoot systems the products produced by leaves will be of limited use for plant survival?Explain how photosynthesis is not possible without the shoot system?
11Hands-on explorationPurpose: locate the structure that helps move water through celery stalkIn a group of 2 design and set up an experiment in class using provided materials:Celery stalkFood coloringBeakersWhat is that structure? Draw a cross section of the celery stalk with the structure labelled